Platform hoists



Sept. 15, 1959 F. E. GREENE 2,903,896

PLATFORM HOISTS Filed Feb. 28, l1955 3. Sheets-Sheet 1 zal Sept 15,'1959 F. E. GREENE 2,903,896

PLATFORM HoIsTs Filed Feb. 28. 1955- 3 Sheets-Sheet 2 irraP/vi/ Sept.15, 1959 F. E. GREENE 2,903,896

PLATFORM HorvsTs Filed Feb. 28, 1955 .'5 Sheets-Sheet 3 an o PLATFORMHOISTS Fred E. Greene, deceased, late of Coloma, Calif., by Cora S.Greene, administratrix, Sacramento, Calif.

Application February 28, 1955, Serial No. 490,952

2 Claims. (Cl. 74-95) The invention relates to improvements in devicesfor raising and lowering materiel and personnel and, more particularly,to devices for raising `and holding temporarily in place buildingmaterials, such as plaster board, used in the construction of houses andother buildings.

It is an object of the invention to provide a platform hoist which isrelatively inexpensive and easy to manufacture, yet which is rugged 4andcapable of delivering long, trouble-free service.

It is another object of the invention to'provide a platform hoist whichis simple to operate and maintain.

It is still another object of the invention to provide a platform hoistwhich is light-weight and highly mobile, and can, ltherefore, be easilymoved from one location to another.

It is a still further object of the invention to provide a platformhoist Which raises and lowers with great rapidity and which, therefore,enables a construction crew quickly to lift a piece of plaster board,for example, to the height required.

It is another object of the invention to provide a material hoist whichnot only enables a carpenter to raise a piece of building material tothe ceiling but which also holds the board in position against theceiling joists while nailing of the board is eected.

lt is a still further object of the invention to provide a platformhoist which is self-stabilizing and which, therefore, permits ofconsiderable unevenness in loading and yet which maintains the platformat all times in a proper horizontal attitude.

It is yet a further object of theY invention to provide a platform hoistwhich, owing to a weight-counter-balancing feature, enables the user toraise the hoist and equipment placed thereon relatively easily andwhich, also, during the lowering of the hoist exerts but little strainor effort on the operating personnel.

It is a still further object of the invention to provide a platformhoist having a brake which permits the platform to be securely locked inany desired elevated position.

It is yet another object of the invention to provide a generallyimproved platform hoist.

Other objects, together with the foregoing, are attained in theembodiment described below and shown in the accompanying drawings inwhich:

Figure 1 is a side elevation of the platform hoist in a position ofmedium elevated height.

Figure 2 is a section taken along the folded planes indicated by theline 2-2 of Figure l.

Figure 3 is a section taken along the offset planes in* dicated by theline 3-3 of Figure 2.

Figure 4 is a plan View showing the gear box and the brake and crankmechanism, the view being generally indicated by the line 4 4 of Figure1, with a portion of the figure being broken away to reduce the extentthereof.

Figure 5 is a vertical section of the brake and crank mechanism to anenlarged scale, the plane of section being indicated by the line 5--5 ofFigure 4.

nited States Patent O 2,901,896v Patented Sept. 15, 1959 ICC Figure 6 isa vertical sectional vieW of the brake and crank mechanism, the plane ofsection being indicated by the line 6--6 of Figure 5.

Figure 7 is a side elevational View of a modified form of the platformstabilizing mechanism, a portion of the gure being broken away to reducethe extent thereof.

Figure 8 is a side elevation of the platform hoist shown insemi-diagrammatic form and showing the platform hoist in lowermostposition.

Figure 9 is a view similar to that of Figure 8 but showing the hoist ina somewhat elevated position.

Figure 10 is a view similar to that of Figure 9 but showing the platformhoist in a still more elevated position.

Figure 11 is a view similar to that of Figure l0 but showing theplatform hoist in uppermost or highest position.

The platform hoist of the invention is susceptible of numerous physicalembodiments depending upon the particular environmental situation to bemet, but -several of the herein disclosed hoists have been made andused, and have performed in an eminently satisfactory fashion.

Supported on ground-engaging wheels 21 is a frame 22 including a pair ofbottom rails 23, top rails 24 and vertical stanchions 26 and 27, bracedby angle supports 28 and 29.

Spanning the stanchions 26 and 27 of the framework are horizontal crossmembers 31 and 33 serving to support a brake and hand crank mechanism 32including a gear box 34.

The mechanism 32 includes `an angle iron 36 secured to the member 31. Abearing sleeve 37 mounted on the angle iron 36 confines and supports arotatable transverse shaft 38. Mounted rigidly on and firmly fastened tothe angle iron 36 is a brake drum 41 having a flange 42. A boss 43 has`a bore 44 serving as an additional journal. To the outermost end 46 ofthe shaft 38 is firmly secured a radial crank arm 47. The free end ofthe crank arm 47 carries brackets 48 having apertures 49 receiving apivot pin 51. Mounted on the pin 51 is a handle 52 having a hand-hold53, and having a cheek 54 provided With an aperture 45 receiving the pin51. The handle 52 pivots about the pin 51 as a fulorum.

When cranking is to be performed, the operator first grasps thehand-hold portion 53 and pulls it in the direction of the arrow 50 intothe outlined position 56, in which the handle projects through and isguided by a slot 55 in the crank arm 47. The crank arm 47 is rotated asthe crank handle 56 is turned and so rotates the shaft 38 and thevarious gears within the gear box 34.

When the crank handle 52 is rotated to the cranking position 56, theuppermost end 61 of the crank handle is rotated to an outlined position62 to release the brake mechanism. Inward swinging or rotation of theuppermost end 61 of the crank handle about the fulcrum, pin 51 isaccompanied by a corresponding swinging or rotation of a pivot pin 63.This passes through an aperture 64 in the crank handle iand throughapertures 66 in straddling straps 67, bent to confine a block 68. A pin69 goes through the block and through apertures 7) in the straps. Theblock 68 is fastened to a stem 71 including a rod 72 slideable in anaperture 73 in a bracket 74 on the crank 47. The rod 72 extends throughan opening 76 in a yoke 77 and is secured therein by a nut 78 inteiposedbetween the yoke 77 and the fixed bracket. A compression spring 79bearing against the bracket '74 urges the rod 72 and yoke 77 downwardly.Mounted on the legs 80 of the yoke 77 by rivets 81 is a brake band 82encircling the brake drum 41. Rotation of the crank handle into thecranking position 56 releases the brake.

Braking is effected by pushing the crank handle to the full lineposition in Figure 5, thus drawing the brake band 82 to engage the fixedbrake drum,

Since the spring 79 is displaced from the center of the fulcrum pin 51,the spring tends to hold the crank handle and the brake in a lockedposition.

When the brake band 82 is firmly against the brake drum, it prevents therotation of the crank arm 47 and the associated parts. When the crankhandle 52 is swung outwardly far enough, the spring 79 not only releasesthe brake but `swings the crank handle the rest of theV way intocranking position.

The gear box 34 includes side Walls 101 and 102 and end Walls 103. Apair of bearings 106 support the end of the shaft 38. Mounted on theshaft 38 is a gear 107 meshing with a spur gear 108 which itself mesheswith a spur gear 109. The spur gears 108 and 109 are mounted on shafts111 and 112 journalled in bearings 113 and 114. Torque from the shaft 38is transmitted through the gear 107 to the spur gear 108 and thencetotheV spur gear 109. The spur gears 108 and 109 rotate equal amounts inopposite directions.

Rotation of the spur gears 108 and 109 is transmitted through the shafts111 and 112 to sprocket chains 116 and 117 reeved about sprocket gears118 and 119 fastened on the shafts 111 and 112.

The sprocket chains 116 and 17 and the attendant hoist structure aresubstantially symmetrical about a plane 20. The description describesthe construction and operation of the mechanism on both sides of theplane 120.

The sprocket chain 117 is reeved about a sprocket gear 121 securelymounted on one end of a transverse shaft 122 journalled within a sleeve123 fast on the supporting stanchions '26. On the shaft 122 are baseblocks 124 and 126, the latter being fast on the sprocket gear 125.Mounted on each of the base blocks 124 and 126 is a primary arm 127including strut members 128 and 129 and a cross brace 131. Mounted onthe outermostends of the arms 127 is a pair of spaced apart sleeves 132and 133 supported by diagonal struts 134 and 135.

Journalled within the sleeves 132 and 133 is a transverse shaft 136having mounted thereon a pair of flanges 138 and 139. Mounted on theflanges 138 and 139 are secondary arms 142 and 143 including struts 144and 145 terminating in sleeves 146 and 147. A pair of pins 148 and 149journalled in the sleeves 146 and 147 car1y a third pair of arms 150 and151 comprising a pair of diverging struts 152 and 153. The struts 152and 153 support a platform framework 154 on which a piece of material155, such as plaster board or plywood, is disposed.

The primary arms 127, the secondary arms 142 and the supports 150 aremoved with respect to each other and to the framework.

Rotation of the left sprocket gear 121 causes a correspending rotation,for example, in a clockwise direction, of the left primary arms 127. Asthe arms 127 are rotated to the position designated 161, the sleeves 132and 133 and the shaft 136 are also moved upwardly. The shaft 136 isrevolved about the center line 162 of the shaft 122. A similarrevolution is imparted to a small sprocket gear 163 secured to the shaftand disposed between the sleeves 132 and 133. Reeved about the smallsprocket gear 163 is a sprocket chain 164 also reeved over a fixed largegear 166 mounted on the sleeve 123. The chain 164 has ends fastened tothe wheel 166 at 167 and 168.

As the left arms 127 are swung upwardly, as shown by the arrow 170, tothe position 161, the upper chain run is progressively reeved off thewheel 166 and translates toward the left in Figure 3 and the lower runis reeved `around the wheel 166. Rotational movement is thus imparted tothe sprocket gear 163 in the counterclockwise direction of the arrow169. When the arms 127 are swung downwardly, as shown by the arrow 171,the sprocket wheel 163 is rotated clockwise, as designated by the arrow172.

The upward clockwise swinging motion of the sprocket wheel 163 and theshaft 136 is accompanied by rotation in a counterclockwise direction ofthe gear 163 and the shaft 136. This swings the secondary arms 142 in acounterclockwise direction about the center line 176.

Preferably, the pivot pins 148 and 149 travel in a vertical lineinclusive of the center line 162 of the shaft 122. The distances betweenthe axes 162 and 176 and between the axis 176 and the axis 175 are madeto coincide, and the root diameter of the gear 163 is made onehalf theroot diameter of the fixed wheel 166. The platform supports are thuscaused to move in a predetermined vertical plane and to retain a fixedhorizontal attitude at all times.

While the parallelism of the pivot pins 148 and 149 and the pairs ofplatform supports at each end of the frame is maintained satisfactorily,an additional assurance of parallelism is provided by a pair of members181 connecting the corresponding pivot pins 148 and 149 at the bottom ofthe platform supports.

Any tendency of the platform and the attached vertical platform supportsto tilt owing to an unbalance of weight thereon is countered by astabilizing mechanism 201. included on each platform support is a strut202 pivoted by a pin 200 to a bracket 203 on the strut 144. At the topof the strut 202 on a pin 199 is a rocking member 204 including a rockerarm 208. A yoke 205 on the arm 208 has arcuate portions 206 and a crossbrace 207. At the intersection of the rocker arm 208 and the cross brace207, the rocking member 204 is pivotally mounted on a pin 210 on ahorizontal brace 211. Extending from the upper yoke arm of the left-handrocking member 208 to the lower yoke arm of the righthand rocking member208 is a first lever 216 connected to the yokes by a pair of sprocketchains 217. Connecting the opposite sides of the yoke arms is a crosslever 218-. This is done by a pair of sprocket chains 219.

The interaction of the foregoing components serves to stabilize theplatform.

Figure 7 illustrates a modified form of the stabilizing mechanismcomprising a left-hand rocking member 231 and a right-hand rockingmember 232, each including a strut 233 mounted on a corresponding pivotpin 199. An upper yoke arm 234 and a lower yoke arm 235 are mounted onthe strut 233 and terminate in a quadrant 236 having teeth 237 andbracing arms 238. The rocking member is pivoted about a pin 239 mountedon a cross brace 241 extending between the adjacent struts of theVertical platform supports. The cross brace 241 serves to transmit anyunbalancing forces from one side of the platform to the other side.

The task of the user in cranking the Idevice to its upper most orlowermost position can be greatly simplified by the provision of aweight counter-balancing mechanism. Rotatably mounted on the bearingSleeve 123 is a wheel 252 having a peripheral slot 253 and a flange251i. Mounted firmly on the sleeve bearing 123 is a collar 256 having aflange 257 adjacent the Wheel flange 254. Over the upper edge 253 of theflange 258 is bent one end of a helical coiled spring 259, the other end261 being in a slot 262 in the wheel 252. The wheel 251 rotates in suchdirection as to store energy in the spring during the lowering of theplatform hoist and to release energy during the lifting of the hoist.This also serves to cushion the hoist when it is being lowered.

Secured in a peripheral slot 253 in the wheel 252 by a fastening 266 isa flexible cable 268 reeved about the Wheel 252 and taking off from thetop side of the large wheel 252, leading to the lower side of a smallwheel 271. This is secured to the transverse shaft 136, the cable beingwithin a slot 272 in the wheel 271 and being fastened by a fastening273.

As the arm 127 rotates in a counterclockwise direction 171, the gear163, the shaft 136 and the rwheel 271 are rotated in a clockwisedirection, as shown by the arrow 172. With the clockwise rotation of thewheel 271, the flexible cable 268 is pulled and the rotatable wheel 252is rotated in a counterclockwise direction. The spring 259, previouslyundistorted, is caused to contract and store energy.

When the hoist is raised, the primary arm 127 is rotated in a clockwisedirection 170 and the energy of the spring 259 causes the Wheel 252 torotate in a clockwise direction. Clockwise rotation of the Wheel 252causes the flexible cable 268 to be pulled toward the right. The forceexerted by the cable to augment the force of the sprocket chain 164 isthus benecial. The energy stored in the spring during the lowering ofthe hoist is released during raising thereof.

The hoist in its lowermost position provides a horizontal platform at aheight convenient for the average workman to load material onto theplatform. The height of the platform at its uppermost position is of theorder of three times the height of the platform in its lowermostposition.

The primary and secondary arms do not extend outwardly beyond the endsof the platform itself and can be reversed so that movement of the armstakes place between the vertical planes 180.

Figure 11 shows the platform hoist at its uppermost location in aneutral or dead center position. As the weight of the structure and theload is imposed vertically downwardly upon the sup-porting members ofthe framework, no rotational component is impressed on the hoistingstructure.

The spring force counterbalances the weight of the struct-ure and loadwhich otherwise would act against the brake mechanism. Thus, even in theintermediate positions, the brake mechanism is assisted.

It can therefore be seen that a platform hoist is provided which attainsin an eminently satisfactory fashion the objects of the inventionheretofore recited.

What is claimed is:

1. A platform hoist comprising a frame, a iii-st shaft journalled insaid fname, a primary arm mounted on said first shaft, a second shaftjournalled on the free end of said primary arm, a secondary arm mountedon said second shaft, ya drum fixed on said frame coaXially with saidiirst shaft, a sprocket coaxially mounted on and rotatable in unisonwith said second shaft and in substantially coplanar relation with saiddrum, 'and a chain reeved about said sprocket and secured at both endsto said drum whereby rotation of said primary am and said rst shaft inone direction effects rotation in the opposite direction of saidsprocket, said second shaft and said secondary arm.

2. A platform hoist comprising a frame, a first shaft journalled in saidframe, `a primary arm projecting radial- 1y from Said rst shaft, asecond shaft journalled on the free end of said primary arm, a secondaryarm projecting radially from said second shaft, a drum fixed on saidframe concentrically with said -iirst shaft, a sprocket securely mountedon said second shaft and concentrically therewith, a chain reeved aboutsaid sprocket and about said drum, means for rotating said rst shaft,and spring means connecting said frame and said second shaft forreleasing energy `as said second shaft turns in one direction ofrotation and for storing energy -as said second shaft lriurns in theother direction of rotation said spring means including a exible cablereeved about said second shaft and tensioned thereby as said secondshaft turns in said other direction of rotation.

References Cited in the tile of this patent UNITED STATES PATENTS226,101 Pfautz Mar. 30, 1880 583,034 Davis May 25, 1897 732,418 KingJune 30, 1903 740,398 Cheves Oct. 6, 1903 2,471,901 Ross May 31, 1949FOREIGN PATENTS 260,087 Italy Sept. 5, 1928 424,764 Great Britain Feb.18, 1935

